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F. Soong, P. Patel, J. S. Y. Lee, D. Wilson, A. Salapatek; Evaluation of the Efficacy of Dexamethasone to Improve the Signs and Symptoms of Dry Eye Syndrome (DES) in a Low Humidity Environment (LHE) Chamber Model. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4657.
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To examine the use of topical dexamethasone to improve the signs and symptoms of dry eye syndrome (DES) in a low humidity environment (LHE) chamber model.
12 patients with DES participated in this randomized, double-masked, placebo-controlled study. Enrollment criteria included OSDI score ≥31.25, corneal & conjunctival staining sum score ≥1 (Oxford scale) and ocular burning or stinging score ≥1 (0-4 scale). All patients were given a 1 week run-in with saline drops prior to exposure to the LHE for 90min for baseline measures (V1). They were then randomized into placebo(6) or dexamethasone(6) groups for tid dosing for 7 days. Patients were instructed to fill out "at-home" environmental symptom diary cards to gauge dry eye symptoms prior to each dose. After treatment, they returned for a repeat exposure to the LHE for comparative measures (V2). Corneal and conjunctival staining, TBUT, and "in-chamber" symptom diary cards were evaluated and analyzed pre and post-chamber exposure. Change from baseline was calculated by comparing V2 to V1.
The LHE maintained temporally and spatially uniform temperature, air velocity and relative humidity (RH≤10%) for both visits and for the entire duration of the visit. Corneal & conjunctival staining sum scores for patients treated with dexamethasone were numerically lower compared to placebo (DEX: -0.63±1.36 vs. PLB: -0.25±1.18, n.s.). In addition, there was a smaller change in the reduction of TBUT in the dexamethasone group compared to the placebo group (DEX: 1.83±3.18 vs. PLB: 1.2±1.4, n.s). Dexamethasone patients also showed a marked and significant reduction in symptom exacerbation in the LHE in V2 versus V1 compared to placebo patients (DEX: -6.5±4.9 vs. PLB: 0.2±4.1, p<0.04). No significant ocular symptom improvement was noted in either group on "at home" environmental symptom diary cards.
The use of topical dexamethasone protected against the exacerbation of signs and symptoms of dry eye syndrome in the low humidity environment chamber model. The LHE is a well-controlled chamber facility capable of evaluating the efficacy of ocular therapeutics on dry eye. The LHE is a sensitive clinical model for testing ocular drug in a small patient sample.
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